Process for treating petroleum hydrocarbons



was.

Aug- 15, 1933- A. G. DAvls I 1,922,528

PROCESS FORTREATING PETROLEUM HYDROCARBONS Filed Dec. Y 1o 1925 PatentedAug. 15, 1933 PROCESS Fon TREATING.

HYDRocARBoN PETROLEUM S V Albert G. Davis, Elizabeth, N. J., assigner,by

mesne assignments,

to Gasoline Products Company, Inc., Wilmington, Del., a Corporation ofDelaware Application December I, 1925 Serial No. 74,507

4 Claims.

This invention relates to improvements in processes for treatingpetroleum hydrocarbons, and refers more particularly to processes forthe production of products having the characteristics of gasoline andthe like.. The system consistS primarily of a-double stage process, thecracking or conversion of the oil taking place in one portion of thesystem, While the distillation of the cracked products is effected inseparate Stages directly connected to the cracking stages and separatedtherefrom by a pressure reduction means.'

The novelty in the invention lies primarily in the return of theincondensible gases withdrawn from the nal stage of separation, whichgases are injected back into the fractionating stage to promoteredistillation of the condensate and absorption of the lighter fractionsof the oil from the reuxed material.

The single .figure is a diagrammatic side elevational view of theapparatus with parts in section and parts broken away.

Referring to the drawing, at 1 is shown a furnace in which are mountedthe heating coils 2 connected by means of a transfer line 3 to a.

heavily insulated forged steel reaction chamber 4. The reaction chamber,in turn, is connected by a transferA line 5 in which is interposed apressure reduction valve 6 to an evaporator 7. 'At 8 is shown afractionating tower in the form of a bubble tower connected by a vaporline 9 to the top of the evaporator and having a vapor line 10 leadingofi:` from the-top thereof to a condenser coil 11 positioned in thecondenser box 12. The discharge line from the condenser coil terminatesin a pipe 13, directing the oil to a gas Separator 14. The gas separatoris equipped with a liquid draw oif line 15 regulated by a valve 16 and agas line 17 controlled by a valve I8. The gas line 17 is divided by Tconnection forming the line 18a controlled by a valve 19 which directsthe gas from the system and a line 2O regulated by a valve 21 which isconnected to the suction side of the pump 22 bymeans of. which the gasis discharged through the line 23 either directly back into the bottomof the bubble tower or it is circulated through a heater 24 by closingthe valve 25 whereby the gas is heated to the desired temperature beforeits introduction or injectioninto the fractionating tower. The

evaporator 7 is equipped with a liquid levelv draw off line 26controlled by a valve 27 through an automatic liquid level regulatingdevice 28. The liquid withdrawn is passed through a cooling coil 29 `andthence vto storage through the lating device.

line`30. In a like manner, the liqid withdrawn from the fractionatingtower through the line 31 is directed through the cooling coil 32 andthence i through the line 33 to a recharging stock tank or to storage.-Instead of cooling the condensate Withdrawnfrom the fractionating tower,it may be recharged directly to the heating coils for retreatment in thesystem. These connections have been eliminated for simplicityV but areeasily made with the charging line.

In operation, the cracking stock is introduced from any convenientsource through the line 34 and is charged by means of the pump 35 intothe top of the fractionating tower, being circulated therethrough in aclosed coil 36. The oil passes thence through the line '37 into theheating coils Where it is raised to a cracking temperature. The velocityof the oil through the heating coils is so regulated that the oilreceives suflicient'heat therein to produce the desired 75 amount ofconversion in the subsequent reaction stage but is not overheated to theextent that there is any substantial deposition of carbon in the coils.The highly heated oil is directedY thence through the transfer line 3 tothe reaction' 30 chamber where the major tion takes place. l

Temperatures of from 550 to 1,000 F. are

maintained in the heating and reaction stages,

portion of the reacwln'le pressures are imposed suicient to pre- 35ventany substantial vaporization ranging from 450 to 1500 pounds persquare inch. The con` verted products are directed from the reactionstage into the evaporating tower through the line 5, pressure beingreduced to substantially 9o atmospheric conditions at the valve 6.`

In the evaporating stage the lighter fractions will distill off, theunvaporized portions being automatically withdrawn by the liquid levelreguprimarily of the heavier oils, such as fuel oil, which are cooledand directed to storage through the line 30. The overhead materialpasses off in vapor form through the line 9 and is introduced into thebottom of the fractionating tower tionation in the tower, the vaporspass overhead through the line 10 and are subjected to a finalcondensing action, being cooled as liquid distillate in the gasseparator 14. The bottoms accumulating in the fractionating tower areautomatically discharged either into the cooler and preheated 70 Thesedrawn oi liquids consist 95 cooling,

2 to a recharging stock storage tank, or, without directly back into theheatingl coil. The incondensible gas taken off from the gas separatorthrough the line 17 may be removed from! the system or portions thereofmay be removed While the remaining gas is recirculated through the pipe20 and pump '22 through the line 23 into the bottom of the fractionatingtower where it is injected into the pool of oil accumulated therein.Under certain conditions it may prove to'be advantageous to preheat thegas priorto its injection into, the fractionating tower. Forthis'purpose, there is interposed in the line 23, a heating coil 23apositioned in a heater 24. This heater serves to raise the temperatureof the recycled gases promoting re- -siderable "quantities ofdistillation of the lighter fractions densate on injection of the heatedgases back into the tower.

It is a well known practice to inject incondensible gases, steam,hydrogen, oxygen or inert gas such as carbonic acid gas, into thevaporizing or reaction stage of the cracking system and heretofore steamhas been injected intolthe fractionating stage of both a crackingAsystem and atmospheric distillation system to promote redistillation ofthe'low boiling point fractions. It is thought novel, however, to returnthe incondensible gases to the fractionatingstage and there inject theminto the fractionating tower where they are combined With the vaporsrising Furthermore, this practice. has given considerable satisfactionlboth vvhere through the tower.

the gases are heated and where they. are unheated, as they absorb fromthe condensate conthe lighter fractions which are separated out duringthe -fractionating of the vapors.

I claim as my invention: l. A process of converting petroleumhydrocarbons, comprising the steps of subjecting the oil to crackingtemperatures and pressures, distilling off the lighter products,removing and fractionating the vapors, subjecting the still unfrom thecon" condensed vapors to a final condensing action and separating thedistillate from the uncondensible gas, returning said gas directly tothe `fractionating stage and percolating it lthrough a pool of thecondensate collected in the bottom of the fractionating stage. 2. Aprocess vfor coverting petroleum hydrocarbons, comprising the steps ofsubjecting the oil to cracking temperatures and pressures, reducing thepressure on the oil and distilling off the lighter products andsubjecting the evaporated products to fractionation, passing uncondensedvapors to a condensing stage, separating the distillate from theuncondensable gases, passing the gas to a heating stage and thereafterreturning it directly to the fractionating stage.

3. A process of converting petroleum hydrocarbons comprising the stepslof subjecting oil to cracking temperatures and pressures, reducing thepressure on the treated oil and distilling off the lighter products,fractionating the evolved vapors in a fractionating stage, condensingthe condensible components of said vapors and returning the incondensblecomponents into a .pool of condensate in th'efractionatin'g stage.l

4. A process for cracking hydrocarbon oil comprisingmaintaining thehydrocarbon constituents under cracking conditions of temperature andpressure in a still, removing vaporous constituents from the still,subjecting the vaporous constituents to dephlegmation in a zone apartfrom the still, subjecting the dephlegmated vapors to condensation,collecting the resulting condensate and uncondensable gases, raising thetemperature of portions of the uncondensable'gases produced in theprocessvto.

above the temperature of the vapors entering the dephlegmating zone andreturning the same directly to the dephlegmating zone to facilitate therelease ofrgasoline-like fractions from the condensate separated fromthe vapors in the dephlegmating zone.

ALBERT G. DAVIS.

